Dissertationen zum Thema „Défaillance mécanique“
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Millet, Olivier. „Vers une compréhension des mécanismes de défaillance des dispositifs microsystèmes“. Lille 1, 2003. https://pepite-depot.univ-lille.fr/LIBRE/Th_Num/2003/50376-2003-223.pdf.
Der volle Inhalt der QuelleDufrénoy, Philippe. „Étude du comportement thermomécanique des disques de freins vis-à-vis des risques de défaillance : application au domaine ferroviaire“. Lille 1, 1995. http://www.theses.fr/1995LIL10181.
Der volle Inhalt der QuelleBelmehdi, Yassine. „Contribution à l'identification de nouveaux indicateurs de défaillance des modules de puissance à IGBT“. Thesis, Bordeaux 1, 2011. http://www.theses.fr/2011BOR14258/document.
Der volle Inhalt der QuellePower electronics has a role increasingly growing up in transport:electric and hybrid vehicles, trains and aircraft. For these applications, security is a critical point, thus the reliability of the power assembly must be optimized. The knowledge of time to failure is very important information for the designers of these systems. Inthis context, an early failure indicator would predict system failuresbefore it becomes effective. In this thesis, we focused on the electromechanical characterization of power transistors: MOSFET and IGBT. Based on these results this electromechanical characterization should help us in the longer term, to highlight an early failure indicator of the power assembly
Baccar, El Boubkari Fedia. „Évaluation des mécanismes de défaillance et de la fiabilité d’une nouvelle terminaison haute tension : approche expérimentale et modélisation associée“. Thesis, Bordeaux, 2015. http://www.theses.fr/2015BORD0266/document.
Der volle Inhalt der QuelleThis work is a part of the research project SUPERSWITCH in which alternatives solutions to the IGBT, are investigated. This solution was used IGBT in power converters in the 600-1200 V breakdown voltage range. The new MOSFET structures based on the super-junction, such as the DT-SJMOSFET and its "Deep Trench Termination", is proposed as an alternative to IGBT. In this context, this thesis focuses on the robustness characterization of the DT2 termination adapted to a planar diode. After a state of the art on unidirectional voltage power components, the power components termination, and power modules reliability, a test vehicle has been designed in order to carry out different accelerated ageing tests and electrical monitoring. The reliability of DT2 termination was evaluated by experimental tests and numerical simulations. An innovative modeling methodology has been proposed. Finally, new structures have been proposed to limit the delamination failure mechanisms and interface charges problems highlighted in this thesis
Pietranico, Sylvain. „Analyse de matériaux pour la modélisation des mécanismes de défaillance dans les modules électroniques de puissance“. Phd thesis, École normale supérieure de Cachan - ENS Cachan, 2010. http://tel.archives-ouvertes.fr/tel-00543040.
Der volle Inhalt der QuelleMeuterlos, Maxime. „Développement de méthodes de normalisation des indicateurs de santé vibratoires pour la surveillance d'ensembles mécaniques basées sur les paramètres d’utilisation. Application à l’hélicoptère“. Electronic Thesis or Diss., Lyon, INSA, 2023. http://www.theses.fr/2023ISAL0097.
Der volle Inhalt der QuelleThe VHMS (Vibration Health Monitoring System) installed on helicopters plays a strategic role in increasing the safety of operators and passengers during flight. These systems consist of recording operational data during flight, particularly vibration-related data, and monitoring the integrity of mechanical components through indicators derived from signal processing. The basic principle is based on the assumption that the appearance of a failure mode generates a characteristic evolution of indicator values. However, one limitation of VHMS systems is the strong dependence of indicators on flight conditions, which can vary rapidly and complex for helicopters. These variations, which are difficult to control, can mask the signature of a mechanical failure, resulting in ambiguity in interpreting the origin of the observed indicator evolution. In this manuscript, normalization methods are developed to estimate normalized vibration indicators, which are insensitive to flight conditions. First, a review of normalization methods commonly used in the literature is presented. Second, a parametric statistical framework modeling vibration indicators is proposed based on cyclostationary modeling of the vibration signal. This parametric framework will be used to construct two approaches to normalizing vibration indicators. The first approach is based on clustering-classification, linking the helicopter flight phases to the statistics of the vibration indicator. Then, a second approach is based on the regression of quantile distribution parameters conditioned on flight parameters that explain the variability of health indicators. In parallel, a sensitivity analysis is conducted to identify these flight parameters
Aime, Stefano. „Dynamic failure precursors in soft matter“. Thesis, Montpellier, 2017. http://www.theses.fr/2017MONTS011/document.
Der volle Inhalt der QuelleMaterial failure is ubiquitous, with implications from geology to everyday life and material science. It often involves sudden, unpredictable events, with little or no macroscopically detectable precursors. A deeper understanding of the microscopic mechanisms eventually leading to failure is clearly required, but experiments remain scarce. The detection of microscopic dynamics in samples under shear is experimentally very challenging, because it requires to combine the highest mechanical sensitivity to strict requirements on the geometry of the whole setup and on the quality of the optical interfaces. In this work we present one of the first successful attempts to measure microscopic failure precursors in model soft solids. Here, microscopic plasticity under shear is observed using a novel setup, coupling a custom-made stress controlled shear cell to small angle static and dynamic light scattering (DLS).DLS is a very powerful technique, but its application to materials under shear is not trivial. In a first step we show a theoretical, numerical and experimental investigation of how DLS may be used as a tool to measure the microscopic dynamics in soft systems under shear. In ideal solids and simple viscous fluids, the displacement field resulting from an applied shear deformation is purely affine. Additional non-affine displacements arise in many situations of great interest, for example in elastically heterogeneous materials or due to plastic rearrangements. We show how affine and non-affine displacements can be separately resolved by DLS, and discuss the effect of several non-idealities in typical experiments.As a model system, this work mainly focuses on a fractal colloidal gel. We thoroughly characterize the linear power-law rheology of the gel, we show that it is very accurately described by the phenomenological Fractional Maxwell (FM) model, and we discuss the possible relationship between the FM model and the microscopic structure of the gel.Under a constant shear stress (creep experiment), the colloidal gel exhibits a fast, elastic deformation followed by a slow sublinear power-law creep, which is eventually interrupted after several hours by an upturn in the shear rate, leading to the delayed failure of the material. Our experiments show that the first power-law regime, nicely described by linear viscoelasticity, corresponds at the microscopic scale to partially nonaffine, yet fully reversible dynamics. Upon deviation from the linear viscoelasticity, a sharp acceleration, localized in time of the nonaffine dynamics is observed. These faster rearrangements precede the macroscopic failure of the gel by thousands of seconds: they thus are dynamic precursors of failure that allow one to predict the fate of the gel well before any rheological measurement.To obtain a more comprehensive picture of material failure, we next address the onset of irreversibility under a cyclic perturbation repeated many times (fatigue experiment). By following the stroboscopic evolution of the system as a function of the cumulated deformation, we observe that as soon as the shear amplitude is increased beyond the linear regime the relaxation rate increases abruptly, indicating that irreversible plasticity is at play. If a large enough stress amplitude is applied, the system on the long run displays delayed fatigue failure, with reminiscences of the one observed in creep. Differences and similarities between the two failure mechanisms are discussed.Finally, the generality of the results obtained on colloidal gels is checked by investigating as second model system a soft colloidal glass. In this case, our experiments indicate that oscillatory yielding is a gradual process, where two relaxation modes contribute to the observed dynamics. Qualitative analogies found with similar systems (e.g. concentrated emulsions) suggest that a general picture might be obtained with our study, which motivates ongoing and future investigations
Bouarroudj-Berkani, Mounira. „Etude de la fatigue thermo-mécanique de modules électroniques de puissance en ambiance de températures élevées pour des applications de traction de véhicules électriques et hybrides“. Phd thesis, École normale supérieure de Cachan - ENS Cachan, 2008. http://tel.archives-ouvertes.fr/tel-00346572.
Der volle Inhalt der QuelleAinsi, la première partie de cette thèse présente les tests expérimentaux réalisés en cyclage actif durant lesquels nous avons cherché à évaluer la tenue des modules IGBT (600V-200A) fonctionnant à différentes températures ambiantes (température de semelle) et différentes températures de jonction (température des puces). Afin de chercher à comprendre les mécanismes physiques mis en jeu dans la dégradation de l'assemblage, les essais ont été arrêtés rapidement dès lors qu'un indicateur de défaillance laissait supposer une initiation de processus de dégradation.
Dans la deuxième partie, nous nous sommes focalisés sur la tenue des brasures substrat/semelle dans des conditions de cycles thermiques passifs. Sachant qu'habituellement le facteur d'accélération retenu pour le vieillissement de ces brasures est l'amplitude des cycles thermiques, nous avons cherché dans cette partie à évaluer non seulement l'effet de l'amplitude des cycles thermiques mais aussi les niveaux des paliers haut et bas sur l'initiation des fissures dans ces brasures et leurs propagation au cours du cyclage.
Enfin, pour comprendre et analyser le comportement de la brasure et de l'assemblage sous les contraintes de cycles thermiques, une étude par simulation numérique est présentée dans la dernière partie. Une étude numérique effectuée sous des conditions de température similaires à celles imposées dans la partie expérimentale a permis de localiser et d'évaluer les contraintes thermomécaniques que subissent les éléments de l'assemblage. Surtout, nous donnons des éléments de réponse permettant d'établir un lien entre les paramètres thermiques du cyclage passif et les grandeurs physiques qui sont influent sur la durée de vie des brasures. Enfin, cette partie se termine sur une étude numérique dans laquelle nous avons cherché à simuler l'effet combiné des cyclages actifs et passifs sur les contraintes mécaniques au sein des modules IGBT afin de rendre compte des contraintes imposées aux modules dans une application réelle.
Brevus, Vitaly. „Analysis of structural elements' integrity after thermomechanical loading“. Thesis, Clermont-Ferrand 2, 2014. http://www.theses.fr/2014CLF22443.
Der volle Inhalt der QuelleThis thesis was performed under the cotutelle agreement between Ternopil Ivan Pul’uj National Technical University (TNTU, Ukraine) and Blaise Pascal University (Clermont Ferrand, France). The thesis was carried out within Pascal Institute of the Blaise Pascal University - Clermont II, the IFMA and the CNRS, in the Scientific Theme “Active and Smart Materials and Multiscale Modeling” of the Mechanics, Materials and Structures Department, and within the French Institute for Advanced Mechanics. The presented thesis belongs to the scientific field of fracture mechanics and material science. The aim of the thesis is to develop the analytical and experimental methodology for the residual lifetime estimation of the superheater collectors at thermal power stations (TPS), taking into account the operational features of thermomechanical loading. Prediction of lifetime is crucial task for continuous operation of heavy loaded structural elements and is a part of a broader problem, covered in the research of the strength and durability of high temperature structural elements in power-generating equipment. The thesis describes the influence of operating temperature on the fatigue crack growth rate and fracture micromechanisms in the material of the superheater collector
Dupont, Laurent. „Contribution à l'étude de la durée de vie des assemblages de puissance dans des environnements haute température et avec des cycles thermiques de grande amplitude“. Phd thesis, École normale supérieure de Cachan - ENS Cachan, 2006. http://tel.archives-ouvertes.fr/tel-00091782.
Der volle Inhalt der QuelleLa première partie de cette étude présente les caractérisations électriques de composants à semi-conducteur, afin de justifier le choix des diodes Schottky SiC et de transistor CoolMOS Si pour une utilisation à haute température. Ces composants sont alors intégrés dans un véhicule de test (module de puissance) adaptée à une localisation sur le réacteur. L'objectif est d'évaluer les performances électriques des éléments actifs à haute température, et la technologie d'assemblage par brasure des substrats céramiques sur une semelle AlSiC. En complément d'une campagne expérimentale, s'appuyant sur un cyclage thermique de grande amplitude, une évaluation numérique des sollicitations dans l'assemblage permettra de mieux comprendre les mécanismes de défaillances et les moyens permettant d'augmenter la durée de vie des modules de puissance dans ces conditions d'utilisation.
Afin de trouver des solutions d'intégration et de chercher à améliorer la durée de vie des assemblages, la dernière partie de cette étude présente les résultats expérimentaux, dans des conditions tout aussi sévères, pour de nouveaux véhicules de test, sans élément actif, composés de substrats céramiques de technologie différente. Les produits testés comportent des céramique AlN et Al2O3 dont les métallisations, avec ou sans dimples, présentent des géométries différentes. Nous évaluerons également, des substrats de technologie AMB avec des solutions DAB et Si3N4. Finalement, une nouvelle étude numérique est réalisée sous ANSYS dans le but d'estimer l'influence ce des substrats céramiques sur la durée de vie de l'assemblage. Finalement, nous tenterons de proposer des règles de conception permettant d'augmenter la durée de vie des assemblages de puissance.
Nahas, Nabil. „Optimisation de la performance de systèmes multi-composants assujettis à des défaillances aléatoires“. Thesis, Université Laval, 2008. http://www.theses.ulaval.ca/2008/25061/25061.pdf.
Der volle Inhalt der QuelleAdokanou, Kokou. „Etude micro et nanostructurale des défaillances d'architectures microélectroniques en environnement humide“. Thesis, Paris Sciences et Lettres (ComUE), 2017. http://www.theses.fr/2017PSLEM064.
Der volle Inhalt der QuelleThis thesis aims at using mechanical stress engineering to improve the reliability of microelectronic components under Temperature-Humidity-Bias testing in order to develop robust packaging technologies for space. The application is done on microware devices based on gallium arsenic (GaAs) with low noise amplifier function (LLA and LNA). We started work by analyzing failure mechanisms of MMIC devices (Monolithic Microwave Integrated Circuit) in severe environment and with the evaluation of thermomechanical induced stresses in stack layers by test temperature. We propose two methods to study the impact of mechanical applied stress on the reliability of microware devices in space qualification: the first method called “indirect” is a bending by buckling way which applies uniaxial stress (250MPa in absolute value) and the second method called “direct” with biaxial stress by treating silicon nitride passivation (SiNx) layer with nitrogen ion implantation (~ -1,2GPa). A system which applies mechanical stress and a printed circuit especially designed for this thesis. Characterization benches with connectors of probes are used to make electrical measurements of transistors and to calibrate the changes of internal stress by piezoresistive effects in semi semiconductors. Numerical simulations have been performed in Abaqus ® to evaluate thermomechanical stresses induced in layers through devices preparation and after plastic encapsulation (Dam&Fill). For each proposed method, aging test was carried out in the most severe conditions (85°C / 85%RH / inverse polarization of the gate). The results of indirect case by buckling on 1850h (A) / 2450h (B) of testing showed a significant improvement of their reliability either in tensile or compressive applied stress. Indeed, for the studied devices the presence of stress delayed considerably damage of more than 80% of aged devices. The failure analysis of failed devices was completed by finite element method simulations in Abaqus ®. We observed and blisters near the gate fingers and capacitors which are linked to the loss of static and dynamic performances. The results in the direct case by surface treatment on 1000h (A and B) of testing also showed the improvement of the reliability for all aged components. The comparison of these results with the indirect case helps to identify the nature and level of optimal applied stress to ensure a better reliability of GaAs devices under THB testing. A study of the physico-chemical behavior of the failures at the surface was also performed in order to make a link between different scales of failure: from the loss of performance until the breaking of chemical bonds through changes of internal stress of the layers
Iasnii, Volodymyr. „Assessment of the limit state of superheater collectors“. Thesis, Clermont-Ferrand 2, 2014. http://www.theses.fr/2014CLF22480.
Der volle Inhalt der QuelleThis thesis has been performed under the cotutelle agreement between Ternopil Ivan Pul’uj National Technical University (TNTU, Ukraine) and Blaise Pascal University (Clermont Ferrand, France). The thesis has been carried out within Pascal Institute of the Blaise Pascal University - Clermont II, the IFMA and the CNRS, in the Scientific Theme “Active and Smart Materials and Multiscale Modeling” of the Mechanics, Materials and Structures Department, and within the French Institute for Advanced Mechanics. The work is included in the Transversal Action "Materials and Multi-scale Modelling" of the Pascal Institute and in the Action MAIM of the Excellence Laboratory Labex IMobS3. The presented thesis belongs to the scientific field of fracture mechanics and material science. The aim of the thesis is to study the effect of operating time on damage of structure, mechanical properties and fracture toughness of superheater collector steel at thermal power plants (TPPs) and to develop the methods that are based on the assessment of the residual strength of collector taking into account the mechanical properties scatter, operational loading and defect sizes. The thesis studies the influence of hydrogenation on mechanical behavior, fracture toughness and fracture micromechanisms in the material of superheater collector at slow deformation
Gousseau, William. „Pronostic de dégradation d'endommagements de roulements sur application aéronautique par analyse vibratoire“. Thesis, Lyon, 2018. http://www.theses.fr/2018LYSEI063.
Der volle Inhalt der QuelleAs part of preventive maintenance of its engines, Safran Aircraft Engines wishes to complete its diagnostic operations with a reliable prognosis of the residual life of the bearings. Following an attack, there is currently a great deal of uncertainty about the remaining life before bearing failure from the threshold of vibrational observability of the damage. Current algorithms diagnose an approximate stage of degradation and generate alarm messages of different levels, each level corresponding to a different stage of degradation, combining confidence and severity of diagnosis. An important aspect of the prognosis is the taking into account of the contextual parameters influencing the rate of degradation. The objectives of this thesis are to have methods and tools to quantify a running time remaining before bearing failure with regard to: - the severity of the damage detected, - the environmental conditions of operation, - the depth The industrial constraints associated with these objectives are as follows: 1) The prognosis should be based, at least, on high-frequency vibratory measurements of a few kHz (accelerometers), contextual data (the rotational speeds of the different rotors, for example, or the amplitudes of the levels piloted on them), rotation regimes, revealing a loading of the bearings) 2). Constituing a database of tests resulting from a plan of experiments: these tests will have to take into account the constraints related to the control of the parameters considered to be significantly influential 3) This database must take into account the representativity of the vibratory environment of an aircraft engine. 4) Propose a tool or method of prognosis taking into account the nature of the bearing to consider
Raid, Idir. „Développement de méthodes numériques et de caractérisations expérimentales pour l’étude des contraintes mécaniques et défaillances induites dans les dispositifs microélectroniques avancés“. Thesis, Université Grenoble Alpes, 2020. http://www.theses.fr/2020GRALI084.
Der volle Inhalt der QuelleThe trend in the microelectronics industry is towards miniaturisation, from transistors to the integrated circuit package. This constant desire of compactness is certainly motivated by economic reasons, but also by the perspectives to gain in performance, power and ergonomics. In early 90s, 0.8 µm was the transistors gate length at major semiconductor manufacturers. The length has been reduced to 6 nm with a density of integration of 125 million transistors per square millimetre. However, such a transition does not come without consequences, as far as it concerns fracture mechanisms, it is particularly true regarding the low-k dielectrics. This family of materials, although porous and fragile, is essential to ensure the insulation in the circuitry of an increasingly dense Back-End of Line (BEoL), with increasingly fine lithography. Besides, due to its porosity, it also has a hydrophilic behaviour which greatly reduces both its insulation quality and stress strength. For all these reasons, the seal ring, the copper interconnection structure that encircles the chip, was implemented to (i) ensure the mechanical integrity of its interior, containing the electrically active part of the die, and (ii) to protect it from moisture and other chemicals intrusions. Hence the interest of this work to address the thermomechanical stresses and cracking phenomena which are articulated around the BEoL. To do so, various paths revolving around the same line of research, mechanical integrity in microelectronics systems, are proposed. (i) Two ways of evaluating stress fields in active silicon and passive BEoL are investigated: by implementing sensor structures based on the principles of piezoresistance and extensometry respectively. (ii) The Four-Point Bending technique is benchmarked, and readapted to account for the crack length, for cracks advancing is homogeneous (decohesion) and heterogeneous (debonding) thin films structures. (iii) A Finite Elements approach, combined with Cohesive Zone Models under Small-Scale Yielding conditions, is proposed to analyse the influence of the arrangement and plasticity of copper in the interconnections in the resistance to crack advance
Razaaly, Nassim. „Rare Event Estimation and Robust Optimization Methods with Application to ORC Turbine Cascade“. Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLX027.
Der volle Inhalt der QuelleThis thesis aims to formulate innovative Uncertainty Quantification (UQ) methods in both Robust Optimization (RO) and Reliability-Based Design Optimization (RBDO) problems. The targeted application is the optimization of supersonic turbines used in Organic Rankine Cycle (ORC) power systems.Typical energy sources for ORC power systems feature variable heat load and turbine inlet/outlet thermodynamic conditions. The use of organic compounds with a heavy molecular weight typically leads to supersonic turbine configurations featuring supersonic flows and shocks, which grow in relevance in the aforementioned off-design conditions; these features also depend strongly on the local blade shape, which can be influenced by the geometric tolerances of the blade manufacturing. A consensus exists about the necessity to include these uncertainties in the design process, so requiring fast UQ methods and a comprehensive tool for performing shape optimization efficiently.This work is decomposed in two main parts. The first one addresses the problem of rare events estimation, proposing two original methods for failure probability (metaAL-OIS and eAK-MCS) and one for quantile computation (QeAK-MCS). The three methods rely on surrogate-based (Kriging) adaptive strategies, aiming at refining the so-called Limit-State Surface (LSS) directly, unlike Subset Simulation (SS) derived methods. Indeed, the latter consider intermediate threshold associated with intermediate LSSs to be refined. This direct refinement property is of crucial importance since it enables the adaptability of the developed methods for RBDO algorithms. Note that the proposed algorithms are not subject to restrictive assumptions on the LSS (unlike the well-known FORM/SORM), such as the number of failure modes, however need to be formulated in the Standard Space. The eAK-MCS and QeAK-MCS methods are derived from the AK-MCS method and inherit a parallel adaptive sampling based on weighed K-Means. MetaAL-OIS features a more elaborate sequential refinement strategy based on MCMC samples drawn from a quasi-optimal ISD. It additionally proposes the construction of a Gaussian mixture ISD, permitting the accurate estimation of small failure probabilities when a large number of evaluations (several millions) is tractable, as an alternative to SS. The three methods are shown to perform very well for 2D to 8D analytical examples popular in structural reliability literature, some featuring several failure modes, all subject to very small failure probability/quantile level. Accurate estimations are performed in the cases considered using a reasonable number of calls to the performance function.The second part of this work tackles original Robust Optimization (RO) methods applied to the Shape Design of a supersonic ORC Turbine cascade. A comprehensive Uncertainty Quantification (UQ) analysis accounting for operational, fluid parameters and geometric (aleatoric) uncertainties is illustrated, permitting to provide a general overview over the impact of multiple effects and constitutes a preliminary study necessary for RO. Then, several mono-objective RO formulations under a probabilistic constraint are considered in this work, including the minimization of the mean or a high quantile of the Objective Function. A critical assessment of the (Robust) Optimal designs is finally investigated
Finck, Laurent. „Modélisation numérique des problèmes de fiabilité en mécanique de la fatigue, de la rupture et du contact“. Besançon, 2001. http://www.theses.fr/2001BESA2005.
Der volle Inhalt der QuelleThe objective of this work is to study the coupling of reliability algorithms with the finite element method applied to the fatigue, fracture and contact mechanical problems. The thesis is divided into five chapters : The first chapter covers the reliability methods in mechanical engineering. The Monte Carlo method and Form (Firts Order Reliability Method) are introduced. The algorithms are programmed and tested on two analytical examples. The second part focuses on the implementation of the first order sensitivities and Form/-Sorm into a finite element analysis code for linear elasticity problems. The example of finite element analysis allows testing several types of random variables. The notion of failure zone is evaluated through elastic-plastic analysis. The third chapter describes the fatigue models. Form is inserted in the same FEM code considering a limit state function depending on the number of cycles to failure. Form is also compared to the notion of safety factors. Numerical examples are presented to show the functionality of Form in fatigue analysis. The fourth chapetr establishes the coupling method between Form and the fracture analysis. Form and the first order sensitivities analysis are performed inside the code using the hybrid mongrel elements of displacement for the computation of stress intensity factors. The last part points out some restrictions when applying Form to the modelling of frictional contact problems. The flexibility method via Implicit Standard Material is chosen for the coupling with Form. The convergence issues are discussed on a test example
Arous, Ahmed. „Stratégies de localisation du (des) composant(s) défaillant(s) pour un système multi-composant“. Thesis, Université Laval, 2012. http://www.theses.ulaval.ca/2012/28861/28861.pdf.
Der volle Inhalt der QuelleIn this paper, we address the problem of the localization of the component(s) responsible(s) for the failure. Each component is subjected to random failures. Some tests help the detection of the state of a component or a subsystem. The objective of this research is to exploit the available knowledge and techniques to generate the tests sequence that locate quickly the (s) component (s) responsible (s) of system failure. We consider a system which operates according to a structure series and of which we know the test costs and the conditional probability that a component (i) is out of service. We analyze the different diagnostic strategies. Some examples, taken from the literature, are used to illustrate each procedure covered. Many extensions are proposed to handle the case where the diagram of the system is not necessarily "series". The algorithms treated are based of probabilistic analysis of systems, the information theory, the heuristic approach and the dynamic programming.
Maskali, Fatiha. „Imagerie radio-isotopique quantitative du remodelage cardiaque ischémique chez le rat : mécanisme et impact de la thérapie cellulaire“. Nancy 1, 2006. http://www.theses.fr/2006NAN11306.
Der volle Inhalt der QuelleGouyou, Doriane. „Introduction de pièces déformables dans l’analyse de tolérances géométriques de mécanismes hyperstatiques“. Thesis, Bordeaux, 2018. http://www.theses.fr/2018BORD0343/document.
Der volle Inhalt der QuelleOver-constrained mechanisms are often used in industries to ensure a good mechanical strength and a good robustness to manufacturing deviations of parts. The tolerance analysis of such assemblies is difficult to implement.Indeed, depending on the geometrical deviations of parts, over-constrained mechanisms can have assembly interferences. In this work, we used the polytope method to check whether the assembly has interferences or not. For each assembly, the resulting polytope of the mechanism is computed. If it is non empty, the assembly can be performed without interference. If not, there is interferences in the assembly. According to the result, two different methods can be implemented.For an assembly without interference, the resulting polytope enables to check directly its compliance. For an assembly with interferences, a study taking into account the stiffness of the parts is undertaken. This approach uses a model reduction with super elements. It enables to compute quickly the assembly with deformation. Then, an assembly load is computed to conclude on its feasibility. Finally, the spreading of deformation through the parts is calculated to check the compliance of the mechanism.The short computational time enables to perform stochastic tolerance analyses in order to provide the rates of compliant assemblies
Hähnel, Anthony. „Approche mécano-probabiliste système en conception pour la fiabilité“. Clermont-Ferrand 2, 2007. http://www.theses.fr/2007CLF21727.
Der volle Inhalt der QuelleKadry, Seifedine. „Couplage éléments finis et méthode de transformation probaliste“. Phd thesis, Université Blaise Pascal - Clermont-Ferrand II, 2007. http://tel.archives-ouvertes.fr/tel-00717847.
Der volle Inhalt der QuelleRoucou, Romuald. „Analyse expérimentale et numérique des défaillances mécaniques locales induites dans les interconnexions par les tests paramétriques et les assemblages : optimisation des procédés et des architectures des plots de connexion“. Phd thesis, Ecole Nationale Supérieure des Mines de Saint-Etienne, 2010. http://tel.archives-ouvertes.fr/tel-00669635.
Der volle Inhalt der QuelleLanternier, Brice. „Retour d'expérience et fiabilité prévisionnelle : mise en oeuvre de modèles et détermination des facteurs influant la fiabilité pour le calcul de taux de défaillance des matériels mécaniques utilisés en tant que dispositifs de sécurité“. Saint-Etienne, 2007. http://www.theses.fr/2007STET4011.
Der volle Inhalt der QuelleFunctional safety assessment requires a safety level quantification of equipments by a qualitative and quantitative analysis. Some industrials whose have no specific feedback for their activities experience difficulties to provide reliable and relevant results. Designers of reliability databases for electronic components have defined models for calculating failure rates depending on the parameters of use. There is nothing in the field of mechanical equipment. This research aims to develop a methodology to improve the predictions reliability of mechanical and electromechanical equipment. Thus, this work implements models that allow accurate prediction reliability taking into account mechanical equipment specificity and influential factors reliability. We propose an analysis method for different feedback based on the quality and quantity of information. This study is only based on operating feedback equipment to take into account influencing factors reliability, the subject of this thesis. Thus, in order to deal with efficiently operating feedback resulting from generic databases, the use of bayesian techniques and weighting of various input data according to pre-defined factors is proposed. The second approach, fully parametric, is based on proportional hazard model to get an environmental function reflecting the impact of factors on reliability. Finally, a neural networks mode is available for numerous operating feedback in quantity and quality
Bereriche, Youcef. „Contribution de l'approche contrainte / résistance à l'évaluation de la fiabilité des structures“. Thesis, Université Laval, 2010. http://www.theses.ulaval.ca/2010/26617/26617.pdf.
Der volle Inhalt der QuelleGuekie, Simo Aubin Thibaut. „Effets de la variation spatiale et temporelle des propriétés des terrains sur les défaillances des réseaux enterrés“. Thesis, Bordeaux 1, 2012. http://www.theses.fr/2012BOR14679/document.
Der volle Inhalt der QuelleThe interactions between shallow groundwater and sewer network are generally complex. The aim of this research is to study the impact of the water table level variation on the damages of the buried pipes. For this purpose, a three-dimensional (3D) numerical groundwater flow model of the shallow multi-aquifer of the Bordeaux urban area, within a 83 km2 area (Mérignac, Pessac, Talence), is developed, calibrated and validated. In order to do this, in a first step, a conceptual model was built based on stratigraphic descriptions of the boreholes. A geostastistical study was carried out to build the limits of the geological layers and the piezometrical maps from the measurement campaigns of water table levels. Then, an original methodology to transform the description of lithological units to local hydraulic conductivity values is proposed and the reconstruction of hydraulic conductivity fields at the urban scale was performed based on geostatistical methods. In a second step, hydrogeological conditions were simulated using the finite-difference groundwater flow model MODFLOW-2005 (Visual Modflow ©). The hydrogeological parameters were then calibrated manually and automatically based on water table elevation data measured in July 2010, October 2010 and March 2010. The model validation covered 6890 days, from June 1993 to may 2012. The results showed that the simulated heads are quite accurate and reproduce the main dynamics of the system at 35 piezometers. The spatial and temporal distribution of the heads of the piezometers simulated permitted to identify the flooding zones of the sewer network by comparing the piezometric head with the altitude of the networks. The sectors where the pipes are damaged were localized in the zone wherein there is low probability of flooding. Additionally, the natural hydrologic environment, taken as a sole factor, cannot explain the pipe breakage phenomena
Koné, Gilles Amadou. „Caractérisation des effets thermiques et des mécanismes de défaillance spécifiques aux transistors bipolaires submicroniques sur substrat InP dédiés aux transmissions optiques Ethernet à 112 Gb/s“. Thesis, Bordeaux 1, 2011. http://www.theses.fr/2011BOR14471/document.
Der volle Inhalt der QuelleThis work presents the implementation of an experimental procedure to evaluate the failure mechanisms of submicron Heterojunction Bipolar Transistor on InP substrate. This procedure presents 3 steps: activation, detection and localization of the failure mechanisms. The accelerated aging tests have been used to active the failure mechanisms on hexagonal shape HBTs with InGaAs or GaAsSb base together with TLM. Due to the electrical analysis through the compact modelling, we established the first hypothesis about the origin of the failure mechanisms. For example, on InGaAs HBT, the failure mechanisms observed are located:- At the emitter sidewall. This mechanism leads to the increase of the base current for VBE<0.6 V- At the base-emitter junction leading to the increase of base and collector current for VBE>0,6 V and 0.20.8 V.These hypotheses were validated by 2D physical simulation using TCAD Sentaurus. The same electrical signatures of the failure mechanisms are observed in literature
Belhenini, Soufyane. „Etude de structures de composants micro-électroniques innovants (3D) : caractérisation, modélisation et fiabilité des démonstrateurs 3D sous sollicitations mécaniques et thermomécaniques“. Thesis, Tours, 2013. http://www.theses.fr/2013TOUR4029/document.
Der volle Inhalt der QuelleThis work establishes a contribution in an important European project mentioned 3DICE (3D Integration of Chips using Embedding technologies). The mechanical and thermomechanical reliability of 3D microelectronic components are studied by employing standardized tests and numerical modeling. The board level drop test and thermal cycling reliability tests are selected for this study. Failures analysis has been used to complete the experimental study. The mechanical properties of elements constituting the microelectronic components were characterized using DMA, tensile test and nanoindentation. Bibliographical researches have been done in order to complete the materials properties data. Numerical simulations using submodeling technique were carried out using a transient dynamic model to simulate the drop test and a thermomechanical model for the thermal cycling test. Numerical results were employing in the design optimization of 3D components and the life prediction using a fatigue model
Diatta, Marianne Amemagne. „Fiabilité des diodes de protection ESD soumises à des décharges électrostatiques répétitives“. Toulouse 3, 2012. http://thesesups.ups-tlse.fr/4126/.
Der volle Inhalt der QuelleThe sensitiveness of components towards electrostatic discharges (ESD) remains a key point in the frame of shrinked technologies. Indeed, industrial developments associated to a harsh environment for more and more smart electronic applications lead to aggressive reliability requirements by customer. Hence, specifications initially dedicated to electronic systems extends to integrated circuits then discrete components. In fact, customers require, in addition to the 15kV robustness for IEC 61000-4-2 norm, to withstand ESD reliability level by specifying immunity of the integrated circuit after applying 1000 discharges of 15kV level. To guarantee this ESD reliability level, especially in a repetitive mode, the methodology developed in this study consists in the understanding of failure mechanisms through physical and electrical characterizations associated to electro-thermal simulations. In integrated circuits, bidirectional diodes often localized at the input and output ensure a protection towards ESD that could occurs during system lifetime. In this context, the study particularly focuses on this discrete protection diode. Physical investigations on repetitive ESD failures describe the failure mechanism from structural defect creation to destruction. Moreover, gathering electro-thermal simulations to experimental results confirms appearance of electro-thermo-migration physical phenomenon during repetitive ESD. As a conclusion, removing the structural defects through a metal barrier considerably improves the ESD endurance and fully satisfy customer requirements while preserving intrinsic performances
Hadžalić, Emina. „Analysis of pore pressure influence on failure mechanisms in structural systems“. Thesis, Compiègne, 2019. http://www.theses.fr/2019COMP2502.
Der volle Inhalt der QuelleThis thesis studies the issue of the overall safety of structures built of heterogeneous and pore-saturated materials under extreme loads in application to fluid-structure interaction problems, such as the dam-reservoir interaction. We propose a numerical model of interaction capable of predicting main tendencies and overall behavior of pore-saturated dam structure interacting with the reservoir in failure analyses of practical interest. The proposed numerical model is first presented in two-dimensional (2D) framework and later extended to three-dimensional (3D) framework. We consider the structure built of porous cohesive material. We assume that the external fluid in interaction with the structure acts as a source of pore saturation. We model the response of the pore-saturated structure with the coupled discrete beam lattice model based on Voronoi cell representation of domain with inelastic Timoshenko beam finite elements enhanced with additional kinematics in terms of embedded strong discontinuities acting as cohesive links. The coupling between the solid phase and the pore fluid is handled with Biot’s porous media theory, and Darcy’s law governing the pore fluid flow. The numerical consideration of internal coupling results with an additional pressure-type degree of freedom placed at each node of the Timoshenko beam finite element, which is later used at the fluidstructure interface. The confined conditions met for external fluid placed in the reservoir enable the modeling of external fluid motion with the acoustic wave theory. For the numerical representation of the external fluid limited to small (irrotational) motion, we choose a Lagrangian formulation and the mixed displacement/pressure based finite element approximation. The end result are the displacement and pressure degrees of freedom per node of external fluid finite elements, which allows for the issue of the fluid-structure interface to be solved in an efficient and straightforward manner by directly connecting the structure and external fluid finite elements at common nodes. As a result, all computations can be performed in a fully monolithic manner. All numerical implementations and computations are performed with the research version of the computer code FEAP (Finite Element Analysis Program). The proposed numerical models of structure, external fluid and ultimately numerical model of interaction are validated in the linear elastic regime of structure response by comparing computed results against reference values obtained either with analytical solutions or continuum models. The numerical simulations in the nonlinear regime of structure response are performed with the aim to demonstrate the proposed coupled discrete beam lattice model capabilities to capture complete macro-scale response and failure mechanisms in pore-saturated structures. Finally, the proposed numerical model of interaction ability to deal with the progressive localized failure of a dam structure built of porous cohesive material under damreservoir interaction for a particular loading program was tested. To account for the temperature effects, the thermal coupling is introduced in the numerical model of the structure
Belmansour, Ahmed-Tidjani. „Évaluation de l'efficacité de lignes de production avec machines multi-états et stocks intermédiaires“. Thesis, Université Laval, 2011. http://www.theses.ulaval.ca/2011/28247/28247.pdf.
Der volle Inhalt der QuelleCroston, Tania. „Etude expérimentale du comportement d'une poutre en béton armé en flexion trois points réparée par matériaux composites (approche probabiliste)“. Phd thesis, Paris, ENSAM, 2006. http://pastel.archives-ouvertes.fr/pastel-00002602.
Der volle Inhalt der QuelleMelle, Samuel. „Analyse et modélisation des phénomènes de chargement de diélectriques dans les MEMS RF : application à la fiabilité prédictive de micro-commutateurs électromécaniques micro-ondes“. Phd thesis, Université Paul Sabatier - Toulouse III, 2005. http://tel.archives-ouvertes.fr/tel-00011359.
Der volle Inhalt der QuelleOuaida, Rémy. „Vieillissement et mécanismes de dégradation sur des composants de puissance en carbure de silicium (SIC) pour des applications haute température“. Thesis, Lyon 1, 2014. http://www.theses.fr/2014LYO10228/document.
Der volle Inhalt der QuelleSince 2000, Silicon Carbide (SiC) power devices have been available on the market offering tremendous performances. This leads to really high efficiency power systems, and allows achieving significative improvements in terms of volume and weight, i.e. a better integration. Moreover, SiC devices could be used at high temperature (>200°C). However, the SiCmarket share is limited by the lack of reliability studies. This problem has yet to be solved and this is the objective of this study : aging and failure mechanisms on power devices for high temperature applications. Aging tests have been realized on SiC MOSFETs. Due to its simple drive requirement and the advantage of safe normally-Off operation, SiCMOSFET is becoming a very promising device. However, the gate oxide remains one of the major weakness of this device. Thus, in this study, the threshold voltage shift has been measured and its instability has been explained. Results demonstrate good lifetime and stable operation regarding the threshold voltage below a 300°C temperature reached using a suitable packaging. Understanding SiC MOSFET reliability issues under realistic switching conditions remains a challenge that requires investigations. A specific aging test has been developed to monitor the electrical parameters of the device. This allows to estimate the health state and predict the remaining lifetime.Moreover, the defects in the failed device have been observed by using FIB and SEM imagery. The gate leakage current appears to reflect the state of health of the component with a runaway just before the failure. This hypothesis has been validated with micrographs showing cracks in the gate. Eventually, a comparative study has been realized with the new generations of SiCMOSFET
Xu, Longfei. „Mechanical behaviour of compacted earth with respect to relative humidity and clay content : experimental study and constitutive modelling“. Thesis, Lyon, 2018. http://www.theses.fr/2018LYSET005/document.
Der volle Inhalt der QuelleCompacted earth is regarded as a granular mixture in which clay plays a role of binder but it also exhibits an important interaction with water. During their service life, compacted earth can be subject to large changes in relative humidity. Those perpetual changes of environmental conditions induce continuous changes of water content of the earth that impact significantly its mechanical performances. The present work aimes at studying the mechanical behavior of compacted earth with respect to relative humidity and clay content. It involves an extensive experimental study and a constitutive modelling. In the first part of this thesis, four kinds of local earth are identified with different clay contents. A comparison of compaction method was then conducted between a double static compaction and dynamic compaction. Three types of specific tests: suction test by filter paper method, shrinkage test and sorption-desorption test were carried out, thereby providing a preliminary insight on the interaction effects between clay and water. In the second part, the impact of clay and moisture contents on the shear behavior of compacted earth was investigated taking into account loading-unloading cycles. Adopting a particular definition of Bishop's effective stress, failure states of all samples were observed to lie approximately on a unique failure line crossing the origin in the (p'-q) plane regardless of matric suction and confining pressure. Finally, based on the above experimental results, a new constitutive model was proposed, based on the theories of Bounding Surface Plasticity and continuum damage mechanics, aiming to simulate mechanical behaviour of compacted earth
Chocat, Rudy. „Évaluation de la fiabilité en tolérance aux dommages pour les composants de moteurs spatiaux“. Electronic Thesis or Diss., Compiègne, 2018. http://www.theses.fr/2018COMP2435.
Der volle Inhalt der QuelleTo succeed their mission, the design of space engines must prevent the whole failure modes following dedicated design rules. The damage tolerance has to ensure the mechanical strength of the component considering the potential presence of a undetected defect which is, in a conservatve way, defined as a crack. To avoid the addition of unknown margins, uncertainties, implied by the use of numerical model, can be treated in the probabilitic framework. The goal of this work is to propose a methodology to assess the reliability (probability of failure), of damage tolernace for space engine components. The small rate of flights, the low targeted probability of failure and the use of models, possibly time consuming, which provide a mixed information respectively quantitative, or qualitaive, for a safe, or failed, component limit the use exting approaches. This work firstly present an orignal method to identify significant variables with a unavailable gradient in the failure region. Then, a reliability assessment methodology is proposed coupling regression and classification to compute low probabilities reducing the number of damage tolerance simulations. Finally, this contribution is applied to academical and damage tolerance test cases to lead to a complex space engine case
Legha, Daniel. „Predictive maintenance and remote diagnosis for electro-mechanical drives of Very High Speed Trains“. Electronic Thesis or Diss., La Rochelle, 2023. http://www.theses.fr/2023LAROS015.
Der volle Inhalt der QuelleThe main objective of this research is to implement predictive and remote diagnosis solutions for the train’s accessibility systems, which are driven by direct current motors. And these systems are the Internal Doors, the Gap Filler, the Passengers’ Access Door, and the Lift. The research tackles multiple predictive maintenance and remote diagnosis equations, such as: Test of the belt tension, for all the types of Internal Doors. The good condition of the door open stopper, for all types of Internal Doors. Signature of proper operation of Internal Doors, using the Big Data recorded signals such as the motor current, motor voltage, door position, speed, position sensors, cycles’ timings, and other contextual information recorded on the subsystem. Signature of proper operation of Gap Filler, which has the same objectives as the signature of proper operation of Internal Doors...Regarding the academic side, the research aims to identify a set of selected failure modes based on the following signals: Motor current, Motor Voltage, Motor position, Motor speed, Position sensors, and contextual data such as the temperature, the cant/tilt... The research aims to study the signals intransient and non-transient regimes, with and without position sensors in some cases, with features engineering based on the time domain, the frequency domain, and time-frequency. Furthermore, the research tackles Machine Learning techniques for data/failure classification. The main objective is to work on signal-based techniques, and if possible, additional investigation will be done using model-based techniques
Rotimbo, Mbourou Donald Romarick. „Contribution à la surveillance et au diagnostic de défauts dans les systèmes de transmission par courroie“. Thesis, Lyon, 2016. http://www.theses.fr/2016LYSES052.
Der volle Inhalt der QuelleIn this PHD, we investigate experimental signals recorded from belt drives with a diagnosis aim of belt tension. Our research works present an exhaustive and thematic bibliography on theory and experimentation in belt drive to complete our insufficient knowledges in mechanical domain. We choosed a theoritical approach nearest real conditions of our belt drives bench. We included time fluctuaction in drive shaft speed and blet changes. Unfortunately, we could not resolve motion equations because existence of numerical limits. All conclusions will be used to understand and interprate experimental results after our signal processing numerical procedures. Our tools panel of numerical process comes from a comparative analysis extracted in several scientific documents and differents algorithms. They dedicate to surveillance, diagnosis and pronostic oriented toward bear and gear defaults. A adaptation in our belt case is necessary with variables parameters (tension, load and/or speed) affecting our case. In our automatic approach, we study several faults in analysis domains : modal, traditionnal (time, frequency, spectrum), synchronous, time-frequency and « cyclostationary » . In this last domain, we extract both comopnent (discret and random), after an previous resmapling operation applying to raw collected signal. Each falut type has a specific signature to discriminate with pertinent condition indications (time, frequency and spectrum domains). All results are discussed at the end of this PHD document. Our developped methods and algorithms are a contribution to process belt drives problems, from exprerimental signals recording with acceleromertes, constraint gauges and optical coders
Rodriguez, obando Diego Jair. „From Deterioration Modeling to Remaining Useful Life Control : a comprehensive framework for post-prognosis decision-making applied to friction drive systems“. Thesis, Université Grenoble Alpes (ComUE), 2018. http://www.theses.fr/2018GREAT086/document.
Der volle Inhalt der QuelleRemaining Useful Lifetime (RUL) can be simply defined as a prediction of the remaining time that a system is able to perform its intended function, from the current time to the final failure. This predicted time mostly depends on the state of deterioration of the system components and their expected future operating conditions. Thus, the RUL prediction is an uncertain process and its control is not trivial task.In general, the purpose for predicting the RUL is to influence decision-making for the system. In this dissertation a comprehensive framework for controlling the RUL is presented. Model uncertainties as well as system disturbances have been considered into the proposed framework. Issues as uncertainty treatment and inclusion of RUL objectives in the control strategy are studied from the modeling until a final global control architecture. It is shown that the RUL can be predicted from a suitable estimation of the deterioration, and from hypothesis on the future operation conditions. Friction drive systems are used for illustrating the usefulness of the aforementioned global architecture. For this kind of system, the friction is the source of motion and at the same time the source of deterioration. This double characteristic of friction is a motivation for controlling automatically the deterioration of the system by keeping a trade-off, between motion requirements and desired RUL values. In this thesis, a new control-oriented model for friction drive systems, which includes a dynamical model of the deterioration is proposed. The amount of deterioration has been considered as a function of the dissipated energy, at the contact surface, during the mechanical power transmission. An approach to estimate the current deterioration condition of a friction drive system is proposed. The approach is based on an Extended Kalman Filter (EKF) which uses an augmented model including the mechanical dynamical system and the deterioration dynamics. At every time instant, the EKF also provides intervals which surely includes the actual deterioration value which a given probability. A new architecture for controlling the RUL is proposed, which includes: a deterioration condition monitoring system (for instance the proposed EKF), a system operation condition estimator, a RUL controller system, and a RUL actuation principle. The operation condition estimator is based on the assumption that it is possible quantify certain characteristics of the motion requirements, for instance the duty cycle of motor torques. The RUL controller uses a cost function that weights the motion requirements and the desired RUL values to modify a varying-parameter filter, used here as the RUL-actuating-principle. The RUL-actuating-principle is based on a modification of the demanded torques, coming from a possible motion controller system. Preliminary results show that it is possible to control de RUL according to the proposed theoretical framework
Rotimbo, Mbourou Donald Romarick. „Apports des techniques d’analyse vibratoire à la compréhension et au diagnostic des phénomènes variables dans les systèmes de transmissions par courroies : exploitation des signaux de jauges de contraintes et de la vitesse angulaire instantanée“. Thesis, 2016. http://www.theses.fr/2016LYSES052/document.
Der volle Inhalt der QuelleIn this PHD, we investigate experimental signals recorded from belt drives with a diagnosis aim of belt tension. Our research works present an exhaustive and thematic bibliography on theory and experimentation in belt drive to complete our insufficient knowledges in mechanical domain. We choosed a theoritical approach nearest real conditions of our belt drives bench. We included time fluctuaction in drive shaft speed and blet changes. Unfortunately, we could not resolve motion equations because existence of numerical limits. All conclusions will be used to understand and interprate experimental results after our signal processing numerical procedures. Our tools panel of numerical process comes from a comparative analysis extracted in several scientific documents and differents algorithms. They dedicate to surveillance, diagnosis and pronostic oriented toward bear and gear defaults. A adaptation in our belt case is necessary with variables parameters (tension, load and/or speed) affecting our case. In our automatic approach, we study several faults in analysis domains : modal, traditionnal (time, frequency, spectrum), synchronous, time-frequency and « cyclostationary » . In this last domain, we extract both comopnent (discret and random), after an previous resmapling operation applying to raw collected signal. Each falut type has a specific signature to discriminate with pertinent condition indications (time, frequency and spectrum domains). All results are discussed at the end of this PHD document. Our developped methods and algorithms are a contribution to process belt drives problems, from exprerimental signals recording with acceleromertes, constraint gauges and optical coders